Objectives: Adaptive interaction with the environment requires the ability to predict both human and non-biological motion trajectories. Prior accounts of the neurocognitive basis for prediction of these two motion classes may generally be divided into those that posit that non-biological motion trajectories are predicted using the same motor planning and/or simulation mechanisms used for human actions, and those that posit distinct mechanisms for each. Using brain lesion patients and healthy controls, this study examined critical neural substrates and behavioral correlates of human and non-biological motion prediction. Methods: Twenty-seven left hemisphere stroke patients and 13 neurologically intact controls performed a visual occlusion task requiring prediction of pantomimed tool use, real tool use, and non-biological motion videos. Patients were also assessed with measures of motor strength and speed, praxis, and action recognition. Results: Prediction impairment for both human and non-biological motion was associated with limb apraxia and, weakly, with the severity of motor production deficits, but not with action recognition ability. Furthermore, impairment for human and non-biological motion prediction was equivalently associated with lesions in the left inferior parietal cortex, left dorsal frontal cortex, and the left insula. Conclusions: These data suggest that motor planning mechanisms associated with specific loci in the sensorimotor network are critical for prediction of spatiotemporal trajectory information characteristic of both human and non-biological motions. (JINS, 2017, 23, 171–184)

On étudie expérimentalement l’écoulement turbulent pariétal produit par l’impact d’un jet frappant normalement un disque coaxial en rotation. La méthode utilisée est l’anémométrie à fil chaud : on mesure les vitesses moyennes, ainsi que les contraintes turbulentes dans un domaine où les effets de l’alimentation par le jet axial et ceux de la rotation du disque sont du même ordre de grandeur. On se place dans le cadre des approximations de couche limite pour obtenir une formulation simplifiée du problème. Par ailleurs, on met en évidence les paramètres sans dimensions qui jouent un rôle significatif. L’étude expérimentale est conduite en faisant varier ces paramètres. L’analyse des résultats expérimentaux fournit les échelles caractéristiques des vitesses et des longueurs, ainsi que le niveau de turbulence. De plus, elle donne des informations sur l’importance relative des différents termes des équations de Reynolds et permet de vérifier la validité de l’approximation de couche limite.

The functions of the somatosensory system are multiple. We use tactile input to localize and experience the various qualities of touch, and proprioceptive information to determine the position of different parts of the body with respect to each other, which provides fundamental information for action. Further, tactile exploration of the characteristics of external objects can result in conscious perceptual experience and stimulus or object recognition. Neuroanatomical studies suggest parallel processing as well as serial processing within the cerebral somatosensory system that reflect these separate functions, with one processing stream terminating in the posterior parietal cortex (PPC), and the other terminating in the insula. We suggest that, analogously to the organisation of the visual system, somatosensory processing for the guidance of action can be dissociated from the processing that leads to perception and memory. In addition, we find a second division between tactile information processing about external targets in service of object recognition and tactile information processing related to the body itself. We suggest the posterior parietal cortex subserves both perception and action, whereas the insula principally subserves perceptual recognition and learning.